ZSPM4521 Datasheet

© 2016 Integrated Device Technology, Inc.

22

January 27, 2016

3

Application Circuits

3.1.

Typical Application Circuit

Figure 3.1

Typical Application Circuit for Charging a Lithium-Ion Battery via Photovoltaic Cells

COUT

LOUT

RSENSE

RREF

Photovoltaic Cells

Battery

RTHM

RPULLUP

(optional)

VDD

RPULLUP

(optional)

VDD

CIN

CVDD

GND

EN

VTHERM

SW

NFLT

VBAT

SCL

PGND

VIN

SDA

VTH_REF

VSENSE

VDD

ZSPM4521

3.2.

Selection of External Components

Note that the internal compensation is optimized for a 4.7µF output capacitor (COUT) and a 4.7µH output inductor

(LOUT). Table 1.3 provides recommended ranges for most of the following components.

3.2.1.

COUT Output Capacitor

To keep the output ripple low, a low ESR (less than 35m

Ω) ceramic capacitor is recommended for the 4.7µF

output filter capacitor. The ESR should not exceed 100m

Ω.

3.2.2.

LOUT Output Inductor

For best performance, an inductor with a saturation current rating higher than the maximum VOUT load requirement

plus the inductor current ripple should be used for the 4.7µH output filter inductor.

3.2.3.

CIN Bypass Capacitor for Input from Photovoltaic Source

For best performance, a low ESR ceramic capacitor should be used for the 10µF input supply bypass capacitor. If

it is not a low ESR ceramic capacitor, a 0.1µF ceramic capacitor should be added in parallel to CIN.